1. Field of the Invention
The present invention relates generally to drilling activities for petroleum production wells and to renovation activities for existing wells to enhance the production capability thereof. More specifically, the present invention concerns a method and apparatus for conveyed high pressure hydraulic radial pulsed jetting in vertical to horizontal boreholes for jet formation of specifically oriented lateral passages in a subsurface formation surrounding a wellbore.
2. Description of the Prior Art
Of particular interest to the present invention is the subject matter of U.S. Pat. No. 7,422,059, issued to Henk H. Jelsma on Sep. 9, 2008 and entitled Fluid Injection Stimulated Heavy Oil or Mineral Production System and U.S. Pat. No. 7,441,595, issued to Henk H. Jelsma on Oct. 28, 2008 and entitled “Method and Apparatus for Single-Run Formation of Lateral Passages From a Wellbore”, which patents are incorporated herein by reference for all purposes.
The terms “lateral passages or lateral bores”, as used herein, is employed to describe a plurality of lateral passages that extend laterally from a wellbore into a subsurface earth formation of interest. It is not intended that this term be restricted solely to a rotary boring or drilling operation. Rather, it is intended that the terms “lateral or radial bores” and “lateral or radial passages” be considered synonymous. The term “bore” is intended to encompass any method of forming a passage in an earth formation extending laterally or radially from a wellbore. For example, lateral or radial passages are presently formed in subsurface earth formation by hydraulic jet blasting, radial drilling, such as by using a drilling system powered by a hydraulic motor. The terms “lateral” or “radial” are intended to identify passages that extend laterally from a wellbore into an earth formation whether the lateral passages are oriented in normal relation with the wellbore or extend upwardly or downwardly or in inclined relation to their intersection with the wellbore. The wellbore or wellbore section from which the lateral passages extend may have a wide range of orientation or inclination, i.e., from vertical to horizontal without departing from the spirit and scope of the present invention.
In general, wells for the production of petroleum products are drilled substantially vertically from a point on the surface of the earth to a desired subsurface zone. In many cases however, it is not possible, desirable or practical to drill wells vertically, so the wells or sections of the wellbores are drilled so as to be inclined or deviated from the vertical. Wells may also be drilled with vertical segments from which deviated segments are drilled and in many cases the deviated segments terminate in substantially horizontal bore sections, especially when a producing formation is rather thin but extends a substantial distance from the point of intersection of the primary or main wellbore with the producing formation. Steerable drilling systems have been developed fairly recently to controllably deviate a wellbore so that it may intersect a subsurface anomaly that is perhaps laterally offset from the initial vertical orientation of the wellbore.
For the production of fluid, such as crude oil or minerals from wells intersecting subsurface production formations, the formation of multilateral passages from a main or principal typically vertical wellbore has been accomplished by rotary drilling or reaming as set forth in U.S. Pat. Nos. 4,880,067, 4,928,767 and RE. 33,660 of Jelsma, or by hydraulic jet blasting as set forth in U.S. Pat. Nos. 5,413,184, 5,853,056 and 6,125,949 of Landers and U.S. Pat. Nos. 6,263,948 and 6,668,948 of Buckman et al. Other related inventions from the standpoint of radial or lateral formation of passages extending from a primary well are presented by U.S. Pat. Nos. 4,497,381, 4,527,639 and 4,787,465 of Dickenson et al, U.S. Pat. Nos. 4,640,362, 4,765,173 and 4,790,384 of Schellstede et al. Later product and process development activity concerning or utilizing hydraulic jet lateral passage formation is presented in U.S. Pat. Nos. 7,422,059 and 7,441,595 of Henk H. Jelsma, identified above.
Other existing lateral passage forming products currently present in the marketplace include devices which contain solid steel strings to achieve vertical drilling using drill bits. These solid steel strings are used for the most part to form lateral passages from vertical wellbores. Steel tool positioning and operation strings are typically incapable of use in deviated sections of wellbores since they will not readily follow the contour of inclined wellbore sections.
A number of existing subsurface lateral passage forming tools that are presently found in the marketplace include drill strings using circulating fluids controlled from surface and provided through pumps. This is disadvantageous because of the excessive wear and high maintenance that occurs as very high jetting fluid medium pressures that are required to develop the necessary fluid pressure for jet blasting of lateral passages. For this reason drill strings are typically used only in conjunction with mechanical subsurface drilling apparatus for drilling lateral passages.
Some existing lateral passage forming products of the marketplace employ jetting systems that direct high pressure water at steady pressure to jet blast through formations to form lateral passages. This passage jetting process is typically rather slow, due to the steady fluid pressure that is employed. It has been determined that variable or pulsing jet blasting of lateral passages is more rapid and more efficient for lateral passage formation. However, it is detrimental to the jet blasting equipment, including coiled tubing or jointed tubing to develop high pressure pulsing pressure at the surface to yield the desired high pressure pulsing at the lateral passage depth of a wellbore. It is considered quite advantageous to develop pulsing high fluid pressure of jet blasting fluid in the downhole environment.
Other existing products found in the marketplace include devices which use abrasive fluids to cut a section of casing and penetrate laterally into the surrounding subsurface earth formation. The use of abrasives in jet blasting fluid is especially detrimental to the service life of surface based pumping equipment.
Currently existing lateral passage forming products found in the marketplace employ rotary mechanical drill systems to penetrate a subsurface formation by rotating drill heads. While such mechanical drilling systems can and have been employed, equipment and processes for drilling multiple lateral passages into a surrounding formation, without retrieving the drilling apparatus from the wellbore between each passage drilling operation, have not been used to date.
Presently existing products of the marketplace have been employed to penetrate the formation with hydraulic force at limited pressure and limited volumes. Such operations are quite slow and expensive in comparison with apparatus and methods for jet blasting lateral passages.
A problem with existing lateral passage forming products and techniques is that they have limited repeatability due to the uncertainty of actual penetration in more dense and compressive rock components. High pressure jet drills are unpredictable in their actual performance of jetting in the downhole environment due to the formation compressive factors that typically exist.
Another problem with existing lateral passage forming products and techniques is that they require multiple trips into a well to jet form a plurality of lateral passages into the formation, and for rotational orientation of a passage jetting mechanism within a wellbore so that the resulting lateral passages are oriented along predetermined azimuths.
A significant problem with existing lateral passage forming systems and techniques is that the use of abrasive materials in the passage jetting fluid is typically very damaging to the surface fluid pumping equipment and adversely affects the porosity and permeability of the producing formations and thus is detrimental to the productivity potential of the well. The use of basic fluids for lateral passage jetting activity can be very detrimental to the producing formation.
Another problem with existing products and techniques for forming lateral passages from a wellbore and into the surrounding subsurface formation is that they tend to become compressed and potentially damaged when vertical loads are applied as a result of space within the surrounding tubing.
It has also been determined that existing lateral passage forming products and techniques is that the small coiled tubing that is presently used with lateral passage forming systems has limited strength and pressure rating, thereby limiting the depth of operation as well as limiting the use of such equipment when higher angle application is desired.